Portable boring apparatuses, also known as line boring machines, are used for machining machinery parts where it would be impossible or impractical to set up said parts on a conventional machine tool (lathe, milling machine, etc.), primarily because of the relatively large size of the parts. Boring machine are specifically used to machine an inner sidewall of the bore (an operation known as “boring”) or to machine a rim of the bore (an operation known as “facing”) to repair damage caused by wear in this particular area.
Typically, a portable boring apparatus comprises a shaft, rotating means to rotate the shaft and a bracket adapted to be temporarily secured on a workpiece, near a bore to be machined. One or more tool attachment is secured to the shaft and holds a tool which contacts the workpiece in or near the bore to thereby machine the bore.
Most portable boring machines have multiple tools attachments or accessories which are used to machine different parts of the bore. One of these accessories is a facing accessory which is used to machine the rim around the bore. To perform a facing operation, the machine is first attached to the workpiece such that the shaft of the machine, coupled to a motor, extends through the bore. A central clamp portion of the facing accessory is clamped around the shaft such that the tool attached to the facing accessory contacts the rim of the bore, and the shaft is spun to machine the rim.
It may be necessary to machine a relatively large surface around the rim of the bore. In this case, to cover the whole surface, it would be necessary to have a facing accessory which extends radially further from the shaft such that the tool would cover the entire surface of the rim to be machined, but this larger facing accessory may not be able to fit into small spaces.
Alternatively, some facing accessories allow some radial movement of the tool relative to the shaft. In this case, the radial movement is usually coupled to the rotation of the shaft, or is done manually using a rod held by an operator standing next to the operating machine, putting the worker at risk of injury.
There is therefore a need for an apparatus that will overcome at least one of the above-identified drawbacks.
Features of the invention will be apparent from review of the disclosure, drawings and description of the invention below.